Sensitization of head and neck squamous cell carcinoma to apoptosis by combinational SMAC mimetic and Fas ligand-Fc treatment in vitro

This study aimed to investigate the in vitro efficacy of three different SMAC mimetics for pro-apoptotic sensitization of HNSCC cells. We evaluated BV-6 in comparison to Birinapant and LCL161, for which pro-apoptotic sensitization effects have been demonstrated. Concentration-dependent response was measured for BV-6 in each cell line with an average IC₅₀ value 8-fold lower than of aforementioned SMAC mimetics. Combination treatment of FasL (log2) and BV-6 (IC₁₀) showed highly significant cell count reductions even in the lowest applied concentration in five cell lines (PCI-1: p = 0.0002, PCI-13: p = 0.0002, Detroit 562: p: p < 0.0001, FaDu: p < 0.0001, SCC-25: p = 0.0047). Synergistic effects (y < 1) were evident in eight out of 10 cell lines (PCI-1, PCI-9, PCI-13, PCI-68, Detroit 562, FaDu, SCC-25 and HaCaT). Annexin V assays revealed in nine cell lines very highly significant (p < 0.001) pro-apoptotic effects of BV-6. Western blots showed a heterogeneous IAP expression following SMAC mimetic treatment. Except for two cell lines, at least the cellular inhibitor of apoptosis protein 1 (cIAP1) was degraded in response to BV-6.For prospective targeted HNSCC therapy, this study identifies SMAC mimetics, particularly BV-6 as the compound with the highest pro-apoptotic potency, as promising antitumor agents.     

Cytotoxic effects of SMAC-mimetic compound LCL161 in head and neck cancer cell lines

Objectives

Head and neck squamous cell carcinoma (HNSCC) is one of the most common tumor entities worldwide. Unfortunately, recent drug developments in other fields of oncology have yielded no efficacy in the treatment of oral squamous cell carcinoma. As a new starting point, we investigated the impact of Fas ligand (FasL) and the SMAC-mimetic compound LCL161 in mono- and combination treatment in HNSCC cell lines.

Methods

Five different cell lines of HNSCC were treated with FasL and LCL161 in mono- and combination treatment. Cytotoxicity was measured via a crystal violet assay. The cell lines were characterized for CD95 (FasL receptor) expression via flow cytometry. The degradation of cellular inhibitor of apoptosis protein 1 (cIAP1) was detected via Western blot.

Results

Incubation with FasL led to a significant decrease in three out of five cell lines. Combination treatment with LCL161 enhanced cytotoxicity significantly. Two cell lines were FasL resistant, but one of them could be resensitized with LCL161. In all cell lines, Western blot analysis showed degradation of cIAP1 after LCL161 application. However, one cell line showed only minor vulnerability to the FasL and LCL161 combination.

Conclusion

This is the first study investigating combination treatment of FasL and LCL161 in head and neck cancer cell lines. Pro-apoptotic effects of the combination were detected in the majority of the cell lines. Interestingly, one of two FasL-resistant cell lines was sensitive to the combination therapy with FasL and LCL161.

Clinical relevance

SMAC-mimetic compounds show promising results in the treatment of other tumor entities in vitro and might be useful drugs to improve HNSCC therapy.

     

Apoptosis in oral lichen planus

Apoptotic cell death may be a contributory cause of basal cell destruction in oral lichen planus (OLP). Therefore. the purpose of this study was to investigate the rate of apoptosis in OLP and the expression of two proteins (FasR and FasL) regulating this process. Biopsies from 18 patients with histologically diagnosed OLP were investigated, with comparison to normal oral mucosa of healthy persons. For visualisation of DNA fragmentation, the TUNEL method was used. In order to characterise the infiltrating cell population (CD3. CD4, CD8) and expression of FasR and FasL, we used an immunohistochemical technique. The results showed that T cells dominated in the subepithelial cell infiltrate. Within the epithelium the apoptotic cells were confined to the basal cell layer, and more apoptotic cells were seen in areas with basal cell degeneration and atrophic epithelium. There was a prominent expression of FasR/FasL in OLP. with a rather uniform distribution throughout the inflammatory cell infiltrate. In the epithelium, the FasR/FasL expression was more abundant in the basal cell area compared to the suprabasal cell layer. In conclusion, apoptosis within the epithelium is significantly increased in situ in OLP compared to normal oral mucosa, and seems to be related to the epithelial thickness.     

Dental follicle cells and cementoblasts induce apoptosis of ameloblast-lineage and Hertwig's epithelial root sheath/epithelial rests of Malassez cells through the Fas-Fas ligand pathway

Hertwig's epithelial root sheath (HERS), epithelial rests of Malassez (ERM) cells, and reduced ameloblasts undergo apoptosis during tooth development. This study examined the effects of dental follicle cells and cementoblasts on the apoptosis of ameloblast-lineage and HERS/ERM cells derived from the enamel organ. We also elucidated the induction pathways and identified the apoptotic pathway involved in this process. Here, we showed terminal deoxynucleotidyl transferase-mediated biotin-dUTP nick-end labeling (TUNEL)-positive HERS cells and reduced ameloblasts near dental follicle cells during tooth development. Co-culturing ameloblast-lineage cell line (ALC) ameloblasts and HERS/ERM cells with either dental follicle cells or OCCM-30 cementoblasts markedly enhanced the apoptosis of ameloblasts and HERS/ERM cells compared with cells cultured alone. However, dental follicle cells and cementoblasts did not modulate the apoptotic responses of co-cultured non-odontogenic MCF10A or KB cells. When ameloblasts + HERS and cementoblasts + dental follicle cells were co-cultured, the expression of Fas ligand (FasL) increased in cementoblasts + dental follicle cells, while the expression of Fas increased in ameloblasts + HERS. Interestingly, recombinant FasL induced ameloblast apoptosis while the cementoblast-induced ameloblast apoptosis was suppressed by the Fas/FasL antagonist Kp7-6. These results suggest that during tooth development, dental follicle cells and cementoblasts induce apoptosis of ameloblast-lineage and HERS/ERM cells through the Fas-FasL pathway, but do not induce the apoptosis of non-odontogenic epithelial cells.     

Suppression of Fas receptor and negative correlation of Fas ligand with differentiation and apoptosis in oral squamous cell carcinoma

Apoptosis and the expression of Fas receptor (Fas) and Fas ligand (FasL) were studied in 8 samples of normal oral mucosa (OM) and in 19 oral squamous cell carcinomas (OSCC) by immunohistochemistry and the TUNEL method. Fas was detected in less than 2% of cells of OSCC compared with 84.3 ± 9.0% of cells in the basal layer in OM. FasL was found to be highly expressed in poorly differentiated lesions (90.9 ± 3.6%), and in cells of both the basal (88.3 ± 4.3%) and central (85.3 ± 5.7%) parts of moderately differentiated lesions, whereas in well-differentiated (WD) lessions expression was considerably lower in both basal (42.7 ± 4.1%) and central (11.5 ± 2.4%) parts. In normal OM FasL was primarily detected in cells of the basal layer, but in a high proportion of cells (84.9 ± 4.3%). Apototic cell death was greater in OSCC (1.6 ± 0.6%) than in OM (0.6 ± 0.2%, P <0.05) and was most pronounced in the central part of WD OSCC (2.3 ± 0.5%). Our results show that Fas is expressed in low quantities in OSCC and that FasL expression correlates negatively with degree of differentiation and apoptosis in OSCC.     

Differential expression of the Fas-Fas ligand system on cytokine-induced apoptotic cell death in mouse osteoblastic cells

Apoptotic signalling, particularly in the Fas-Fas ligand (FasL) system, was studied in a mouse osteoblastic cell line, MC3T3-E1. A combination of the cytokines tumour necrosis factor-alpha, interleukin-1beta and interferon-gamma activated the Fas-FasL-dependent cell-death system. The cytokines caused significant enhancement of Fas mRNA and Fas protein, and led to apoptotic cell death. Western blot demonstrated that FasL protein was continuously present in MC3T3-E1 cells, although the cytokines had no effect on the induction of FasL. Exogenous FasL caused a decrease in cell viability and a large increase in apoptotic cell death in cells pre-treated with cytokines, indicating that the Fas-FasL system has the potential to cause apoptosis in osteoblastic cells. Treatment with anti-Fas IgG (antagonistic antibody) inhibited the DNA fragmentation induced by cytokines in a dose-dependent manner, suggesting that cytokine-induced Fas may cause apoptotic cell death in MC3T3-E1 cells. Taken together, these findings show that cytokine-induced apoptotic cell death was mediated by the autocrine or paracrine Fas-FasL system in mouse osteoblastic cells, and suggest that cytokine-induced apoptosis could have an important role in localised bone destruction associated with inflammatory bone diseases such as periodontal disease.     

维甲酸对人舌鳞癌细胞株Tca83 Fas/FasL基因表达的影响

目的探讨不同浓度全反式维甲酸（all-transretinoidacid,简称RA）,在不同作用时间下对人舌鳞癌细胞株Tca83诱导凋亡过程中,相关凋亡基因Fas/FasL的表达及两者之间可能的关系。方法采用TUNEL法检测RA作用下细胞发生凋亡的情况;应用RT-PCR和细胞免疫组化方法检测药物作用组和对照组细胞Fas蛋白水平和mRNA水平的表达。结果TUNEL法显示生理药物浓度1-10uRA作用到第5d时可见明显的凋亡细胞出现,与对照组相比差异有显著性(P<0.05)。相应的RT-PCR亦显示RA作用到5d时FasmRNA水平明显提高,而细胞的FasLmRNA水平却没有改变。细胞免疫组化结果也显示RA可增强Fas抗原的表达。结论RA能诱导Tca83的凋亡基因Fas的表达。提示临床上可利用RA作为先期诱导药或与增强Fas表达的药物、抗Fas抗体联合应用,以增强RA药效,降低不良反应。     

High-fluoride acitivates the FasL signalling pathway and leads to damage of ameloblast ultrastructure

ObjectiveHigh fluoride can induce stress-mediated apoptosis and degradation of ameloblasts. Fas ligand (FasL) has been regarded as a key regulator in intracellular responses for stress-induced apoptosis in reproductive or cancerous cell lineages. The objective of this study is to explore the role of FasL in the regulation of ameloblast ultrastructure damage.DesignPrimary ameloblasts were isolated from the molar tooth germ of 4-day-old SD rats. The ameloblasts were incubated with 3.2 mM NaF or nothing. After incubation for different time arranging from 12 h to 72 h, ELISA was used to detected the secretion levels of FasL in the medium. Then at 48 h post treatment, the ameloblast ultrastructure was detected with Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM), and expression of apoptotic proteins and peroxidative enzymes/products were examined. Finally, a specific FasL inhibitor was applied to co-treat the ameloblasts with NaF, and the ameloblast ultrastructure was detected with TEM and SEM.ResultsThe secretion of FasL was notably increased by 3.2 mM NaF treatment, and the increase reached to the peak after incubation for 48 h. High fluoride incubation damaged the ameloblast untrastructure manifesting a series of intracelluar stress responsing cell organelle destruction, and a marked increase in expression of apoptotic genes and oxidative stress. The FasL inhibitor treatment partially mitigated the untrastructure damage caused by high dose NaF.ConlusionHigh-fluoride leads to damage of the ameloblast ultrastructure through paritially acitivating the FasL signalling pathway.     

口腔黏膜癌前病变及鳞癌中Fas/FasL的表达研究

目的 :研究凋亡相关基因Fas/FasL在口腔正常粘膜、上皮单纯增生、上皮异常增生和鳞癌中的表达及意义。方法 :采用SABC免疫组织化学方法检测正常口腔粘膜 ( 10例 ) ,上皮单纯增生 ( 8例 ) ,上皮异常增生 ( 2 0例 ) ,鳞癌 ( 32例 )中Fas/FasL的表达。结果 :在正常口腔粘膜中Fas表达于棘层和粒层细胞的胞膜 ;FasL局限于基底层细胞的胞膜和胞浆。上皮异常增生中随异常增生程度的增高 ,Fas表达降低 ;FasL表达增强 ,甚至遍布上皮全层。鳞癌组中Fas表达明显低于正常组 (P <0 .0 5 ) ,且与组织学分级呈正相关 ;FasL表达明显高于正常组 (P <0 .0 5 ) ,且与组织学分级呈负相关。结论 :Fas在调节鳞状上皮细胞自我更新中具有重要作用。Fas表达水平下调 ,FasL上调 ,可能是口腔上皮癌变过程中的一个早期事件。Fas/FasL是肿瘤细胞逃逸肿瘤反应T细胞攻击而获得免疫赦免的重要机制之一。     

Fas-FasL在腮腺多形性腺瘤及腺样囊性癌中的表达及意义

目的　观察Fas FasL系统在腮腺正常组织、多形性腺瘤及腺样囊性癌中的表达 ,并探讨其意义。方法　应用免疫组化及图像定量分析技术 ,检测 2 1例正常腮腺、3 5例腮腺多形性腺瘤、3 2例腮腺腺样囊性癌中Fas和FasL的表达 ,并进行统计学处理。结果　Fas及FasL在腺样囊性癌中呈阴性表达 ,且与组织学类型、病理分级无相关性 ;而在正常腮腺及腮腺多形性腺瘤中均有明显表达 ,但多形性腺瘤中Fas及FasL表达低于正常腮腺 ,其差异具有显著意义 (P <0 .0 1)。结论　Fas FasL系统的表达及介导的凋亡失调与腮腺多形性腺瘤和腺样囊性癌的发生、转归有重要关系     

口腔异常增生上皮及鳞癌组织中Fas、FasL及Bcl-2的研究

目的:研究凋亡相关基因Fas、FasL及Bcl-2蛋白在口腔黏膜异常增生上皮及鳞癌组织中变化规律。方法:采用免疫组织化学SP法检测口腔黏膜异常增生上皮及鳞癌组织中凋亡相关基因Fas、FasL及Bcl-2蛋白表达。结果:发现Fas表达水平无差异,但Fas染色在正常、单纯性增生、轻度异常增生组织中以胞膜型为主,而原位癌及鳞癌组织中以胞浆型为主,中度异常增生时两型兼有;FasL在鳞癌组织中过度表达,与对照组、单纯增生组比较差异显著(P<0.05),FasL表达与局部浸润的淋巴细胞呈负相关(r=-0.437,P<0.05)。Bcl-2表达在原位癌时出现高峰,与对照组、单纯增生组比较差异显著(P<0.05),Bcl-2表达水平与Fas L表达水平相关显著(r=0.337,P<0.05)。结论:Fas、FasL及Bcl-2参与了口腔癌前病变癌变发生发展过程,作用的机制可能是它们分别或协同作用抑制细胞凋亡、延长异常细胞生存期、利于免疫逃逸,为细胞癌变提供了条件。     

口腔扁平苔藓固有层淋巴细胞中Fas及Fas配体的表达变化

目的 检测Fas及Fas配体(Fas ligand,FasL)在口腔扁平苔藓(oral lichen planus,OLP)固有层淋巴细胞中的蛋白表达,探讨Fas、FasL和活化诱导的细胞死亡(activation-induced cell death,AICD)与OLP发病的关系.方法 采用脱氧核糖核苷酸末端转移酶介导的原位缺口末端标记法检测31例OLP和10例正常口腔黏膜(normal oral mucosa,NOM)中淋巴细胞凋亡情况;分别使用免疫组化法检测组织总淋巴细胞及CD8~+、CD4~+T细胞Fas、FasL的表达.结果 OLP与NOM固有层淋巴细胞凋亡率[分别为(1.9±1.8)%、(11.5±9.0)%]差异有统计学意义(P=0.013).OLP淋巴细胞Fas、FasL表达与NOM组相比明显增强[阳性表达率分别为52%(16/31)、71%(22/31),P值分别为0.005、0.000].OLP中CD8~+与Fas~+细胞双阳性表达率为10%,与NOM组相比无明显升高(P=0.313),而CD8~+与FasL~+细胞双阳性表达率[58%(3/31)]显著升高(P=0.002).CD4~+与Fas~+细胞双阳性表达率为35%(11/31),较NOM组显著升高(P=0.031),其中网纹型的表达明显升高(阳性表达为8/19,P=0.019),但糜烂、萎缩型的表达无显著升高(阳性表达为3/12,P=0.097).CD4~+与FasL~+表达率为16%(5/31),与NOM组相比无明显增强(P=0.182).结论 OLP淋巴细胞凋亡低下;OLP中T细胞亚群Fas、FasL表达不均衡,CD8~+细胞和萎缩、糜烂型OLP中CD4~+细胞可能逃逸AICD,与炎症的持续和进展有关;网纹型OLP中部分CD4~+T细胞可能经历AICD.     

Interferon‐Gamma and Fas Are Involved in Porphyromonas gingivalis–Induced Apoptosis of Human Extravillous Trophoblast‐Derived HTR8/SVneo Cells via Extracellular Signal‐Regulated Kinase 1/2 Pathway

Background: A number of studies recently revealed a link between periodontal disease and preterm birth (PTB). PTB can be induced by dental infection with Porphyromonas gingivalis (Pg), a periodontopathic bacterium. This study aims to investigate responses of human extravillous trophoblast‐derived HTR8/SVneo cells to Pg infection. Methods: Cell apoptosis, cell viability, protein expression, and cytokine production in HTR8 cells were measured via: 1) flow cytometry, 2) CCK‐8 assay, 3) western blot, and 4) enzyme‐linked immunosorbent assay methods, respectively. Results: Pg decreased cell viability and increased cell apoptosis, active caspase‐3 and Fas expression, and interferon‐gamma (IFN‐γ) secretion in HTR8 cells. Extracellular signal‐regulated kinase (ERK) 1/2 inhibitor U0126 and FasL neutralizing antibody NOK1 that blocks FasL/Fas interaction both significantly suppressed Pg‐induced apoptosis. U0126 also inhibited IFN‐γ secretion and Fas expression close to control levels. Moreover, treatment with recombinant IFN‐γ also significantly decreased number of viable HTR8 cells and increased Fas expression, suggesting IFN‐γ may play an important role in Pg‐induced apoptosis of HTR8 cells, at least partially through regulation of Fas expression. Conclusions: To the best of the authors’ knowledge, this is the first study to demonstrate Pg induces IFN‐γ secretion, Fas expression, and apoptosis in human extravillous trophoblast‐derived HTR8/SVneo cells in an ERK1/2‐dependent manner, and IFN‐γ (explored by recombinant IFN‐γ) and Fas are involved in Pg‐induced apoptosis. The finding that Pg infection abnormally regulates inflammation and apoptosis of human trophoblasts may give new insights into the possible link of PTB with maternal periodontal disease and periodontal pathogens.     

Fas/FasL在牙髓炎症过程中的分布及意义

目的：观察Fas/FasL基因及其蛋白在正常牙髓和炎症牙髓中的表达和分布，探讨其在牙髓炎症过程中的作用机制。方法：采用免疫组织化学染色及原位杂交方法。结果：正常牙髓组织中Fas表达量不高，FasL呈阴性表达，而在牙髓炎症过程中两者均有阳性表达，且其组织细胞的分布与TUNEL法的结果相似。结论：牙髓炎症过程中的细胞凋亡可能是通过Fas介导的LPS等一些因素可能使牙髓组织细胞膜上的Fas和FasL的表达量增加，从而通过其介导的信号转导途径引起细胞凋亡。     

Lipopolysaccharide-induced suppression of periodontal ligament cell proliferation and apoptosis are strengthened under high glucose conditions

The present study aimed to investigate the effect of lipopolysaccharide (LPS) on the proliferation and apoptosis of human periodontal ligament (hPDL) cells under normal glucose or high glucose conditions. Primary cultures of hPDL cells were prepared from extracted premolars of patients. The cells were incubated with 0, 1, or 10 μg/mL LPS under normal glucose (5.5 mmol/L) or high glucose (25 mmol/L) conditions for 24 h or 48 h. Cell proliferation was detected using a CCK-8 assay, and cell apoptosis was measured by Hoechst 33258 staining and Annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI) double staining. BCL2 and BAX mRNA and protein levels were measured by real-time polymerase chain reaction and western blotting, respectively. LPS (10 μg/mL) induced significant inhibition of cell proliferation and cell apoptosis, and a significant decrease in the BCL2/BAX ratio in the cells cultured with 5.5 mmol/L glucose. These effects of LPS were increased significantly in cells treated with 25 mmol/L glucose. Analysis of variance of the factorial design revealed that high glucose and LPS had a significant interaction for cell apoptosis, but not for cell proliferation. High glucose augmented LPS-induced hPDL cell apoptosis and cell proliferation inhibition. LPS and high glucose might interact to induce cell apoptosis.     

口腔黏膜癌前病变和口腔鳞癌组织Fas/FasL的表达及其意义

目的：研究调亡相关基因Fas／FasL在正常口腔黏膜、上皮异常增生和口腔鳞癌组织中的表达及意义。方法：应用免疫组织化学方法检测10例正常口腔黏膜、26例上皮异常增生、38例口腔鳞癌组织及肿瘤浸润淋巴细胞（TIL）中Fas／FasL的表达。结果：Fas在正常口腔黏膜中广泛表达；上皮异常增生和鳞癌组织表达明显下调（P〈0．05）；Fas表达与口腔鳞癌分化程度有关；FasL在正常口腔黏膜不表达；上皮异常增生和鳞癌组织表达明显上调（P〈0．05）；FasL表达与口腔鳞癌分化程度无关（P〉0．05）；TIL细胞Fas、FasL阳性表达率为81．6％和84．2％。结论：Fas表达与口腔黏膜上皮细胞的自然分化成熟、衰老及口腔鳞癌的形成和肿瘤的恶性度有关；FasL的表达上调可能是口腔鳞癌组织免疫反攻击的体现；Fas、FasL可作为监测口腔上皮癌变的标记物。     

The Role of Factors Associated With Apoptosis in Assessing Periodontal Disease Status

Background: Little is known about the release of apoptotic proteins during periodontal breakdown. This pilot study investigates the presence of factors associated with apoptosis in serum, saliva, and gingival crevicular fluid (GCF) and their association with periodontal disease severity and activity. Methods: GCF, whole saliva, and serum were obtained from 47 adult patients with chronic periodontitis (CP) and 10 healthy controls. Clinical measurements, including probing depth (PD), clinical attachment level (CAL), and radiographs, were used to classify patients into healthy, mild, and moderate/severe CP groups. Enzyme‐linked immunosorbent assays were used to measure apoptosis or DNA fragmentation in GCF and active caspase‐3, soluble Fas (sFas), and sFas ligand (sFasL) in saliva and serum. Western immunoblotting was used to detect Fas, FasL, sFasL, and caspase‐3 expression in GCF. Results: DNA fragmentation was positively correlated with PD and CAL regardless of patient disease status (P <0.001). sFas and sFasL were present in saliva and serum, but there were no differences between groups. In GCF, the greater odds of detecting Fas, sFasL, and caspase‐3 increased with increasing PD and CAL (P <0.05). In addition, sites with inflammation and PD ≥5 mm had significantly greater odds of exhibiting Fas, sFasL, and caspase‐3 expression compared with sites without inflammation and PD <5 mm (P <0.05). Caspase‐3 was not detected in saliva or serum. At the patient level, only FasL and disease status were significantly correlated (P <0.05). Conclusion: Factors associated with apoptosis were detected in GCF in patients with CP.     

高浓度肿瘤坏死因子-α环境下髁突软骨细胞死亡情况研究

目的    探讨高浓度肿瘤坏死因子-α（TNF-α）环境下髁突软骨细胞的死亡情况。方法    临床收集2012年9月至2014年8月就诊于上海交通大学医学院附属第九人民医院口腔外科的髁突骨折患者无法复位的骨折片段上的软骨组织,体外培养人髁突软骨细胞,加入20 μg/L TNF-α后流式细胞仪分析细胞死亡情况（T组）,分别与加入泛caspase抑制剂Z-VAD-FMK（ZT组）、特异性程序性坏死抑制剂Nec-1（NT组）和联合应用抑制剂（ZNT组）的细胞死亡情况进行比较和统计学分析。结果    T组细胞大量死亡,剩余活细胞中活性氧（ROS）水平升高;ZT、NT和ZNT组细胞死亡和ROS水平显著低于T组（P < 0.05）,ZNT组细胞死亡和ROS水平最低。结论    高浓度TNF-α刺激下髁突软骨细胞的死亡类型有凋亡和程序性坏死,同时抑制二者可以显著提高软骨细胞的存活率。     

肿瘤坏死因子相关凋亡诱导配体及其受体在头颈部肿瘤的研究进展

肿瘤坏死因子(TNF)相关凋亡诱导配体(TRAIL)是 TNF 家族中继 TNF 和 Fas 抗原配体之后发现的又一重要的新成员,具有诱导肿瘤细胞、转化细胞等发生凋亡而对正常细胞无凋亡诱导作用的特点.自发现至今,因其对肿瘤细胞的选择性而被人们关注并逐渐发展成为靶向肿瘤治疗研究的热点.本文将对TRAIL的特性,TRAIL及其受体诱导凋亡的分子机制,以及TRAIL为靶点的基因治疗和作为抗肿瘤药物在各类肿瘤尤其是头颈部恶性肿瘤中的应用进展及前景展开综述.     

Actinobacillus actinomycetemcomitans induces apoptosis of T lymphocytes by the Fas and Fas ligand pathway

Actinobacillus actinomycetemcomitans expresses a number of toxins capable of inducing apoptotic cell death of T lymphocytes. However, the exact mechanism(s) has not been elucidated. The present study investigated the involvement of the Fas (CD95)-mediated apoptotic pathway in A. actinomycetemcomitans-induced T-cell apoptosis. To that end, peripheral blood mononuclear cells (PBMC) were cultured with or without A. actinomycetemcomitans cell-free culture supernatant (CFCS) for 0-96 h. The cells were then labeled with specific monoclonal antibodies and flow cytometry was performed. Results demonstrated up-regulation of Fas and activation of caspase-3 in T cells in response to A. actinomycetemcomitans CFCS. Monocytes were the only cells analyzed to express Fas ligand (FasL) constitutively, and this was further up-regulated in response to A. actinomycetemcomitans CFCS, while T cells expressed FasL only after this stimulation. Depletion of monocytes prior to stimulation with A. actinomycetemcomitans CFCS led to a marked decline in apoptosis. Blocking of Fas-FasL interactions with anti-Fas monoclonal antibody or Fas:Fc fusion protein lead to a significant decline, but not abolition, of T-cell apoptosis. Nearly all T cells expressed Bcl-2 at the outset of culture, and Bcl-2 expression declined in T cells stimulated with A. actinomycetemcomitans CFCS. Collectively, these data provide evidence for the induction of T-cell apoptosis by A. actinomycetemcomitans via the Fas-mediated pathway, involving caspase-3 and Bcl-2. Moreover, this apoptotic response was dependent on the presence of monocytes.